Since replacing the bearings in my Myford Spindle I set out to get things to run as true as possible. One way was to make an adjustable backplate for my Chuck. We start out with a piece of cast iron and cut it to the dimenision of my Chuck.
In the first photo I am cutting an opening to fit the original adapter plate which we will turn down to 2.75" at a depth of .375".
Next was to turn the adapter plate to .020" smaller then the opening in the adjustable backplate.
Using the DRO function I drilled the mounting holes in the adapter plate and adjustable backplate.
After assembling I mounted it to the lathe and faced it true to the lathe axis and finished cutting the outside diameter to the chucks diameter.
I needed to drill the adjustment holes and tap them after final dimensions.
After making three 1/4x40 screws out of tool steel they were hardened. The Chuck was mounted to the lathe and trued with the three adjusting screws.
After doing the alignment on the Chuck I till seem to have play in my spindle even with it adjusted as far as I can get it. I am beginning to think my front spindle bushing is oval shape like Gray had said. I will investigate this tomorrow. I do have a new bushing but will have to make a tool to remove it with and a tool to reinstall the new one.
Don